This invention relates to a cooling apparatus for use in a charging device of a shaft furnace. More particularly, the present invention relates to a novel cooling apparatus which is an improvement of the charging installation disclosed in U.S. Pat. Nos. 3,880,302 and 3,814,403.
The bell-less charging device for a shaft furnace such as described in U.S. Pat. Nos. 3,880,302 and 3,814,403, both of which are assigned to the assignee hereof and incorporated herein by reference, is well known to those skilled in the art. This type of charging apparatus is widely used because of its superior features, including its superior charging capabilites and its ability to withstand difficult operating conditions such as very high temperatures and an environment consisting of corrosive dust and other abrasive materials.
Typically, a charging device as disclosed in U.S. Pat. Nos. 3,880,302 and 3,814,403 essentially comprises a fixed feed channel positioned vertically within the center of a furnace head, a rotary shell mounted coaxially around the feed channel and a fixed outer frame mounted coaxially outside the rotary shell thereby defining a substantially annular chamber. This chamber is separated, although not isolated, from the interior of the furnace by means of a rotary disc or jacket which is integral with or rigidly connected to the rotary shell. The rotary shell and the attached disc or jacket constitute a rotary housing, with the shell being an upper housing element and the disc or jacket being a lower housing element. The charging device also includes a distribution spout which is pivotally mounted to the rotary jacket. Finally, a first driving means urges the shell, the jacket and the spout to rotate as a single unit about the vertical axis of the furnace and the feed channel while a second driving means imparts pivoting movement to the spout, independently of the movement caused by the first driving means, about the horizontal axis by which it is suspended from the housing.
Charging devices as hereinabove described have been supplied with cool inert gas circulating under pressure in order to minimize the deterioration of exposed components caused by the previously mentioned abrasive and corrosive materials. This cooling system has served a dual purpose. First, the compressed gas cools the component parts which it contacts. Secondly, as the cooling gas circulates at a higher pressure than that pressure which prevails inside the furnace, a pressurized current is directed towards the interior of the furnace and through the gaps between the fixed components and the moving component parts. This pressurized gas current prevents abrasive and corrosive dust from ascending into the annular chamber (which contains driving and/or control mechanisms).
The above described gas cooling system which is currently used has certain advantages and disadvantages. For example, as an advantage, the conventional gas cooling system does not require any additional structure in the charging installation, thereby providing initial low cost. Conversely, accessory equipment for cleaning, cooling and compressing the gas is extremely expensive while also being energy and labor intensive (such as for maintenance). Accordingly, the costs of continued operation and maintenance of a gas cooling system can become extremely expensive.
It has been suggested that one way of reducing these costs would be to replace the cooling system with a water cooling system. Unfortunately, it has heretofore been impossible to practicably construct such a workable water cooling system. The perfection of an adequate water cooling system has been particularly difficult when attempting to construct hermetically sealed and durable flow passages between the fixed component parts and the moving parts to be cooled.